NEW YORK (CNNMoney) -- A proposed new bill intended to combat online piracy has sparked a giant backlash from big tech companies, including Google and Facebook, who say the proposals are far too strict and rife with unintended consequences.

The Stop Online Piracy Act (SOPA), which was introduced in the House of Representatives in late October, aims to crack down on copyright and trademark issues. Its targets include "rogue" foreign sites like torrent hub The Pirate Bay.

Protecting content is a worthy goal, but here's the flip side: Opponents say SOPA -- and a similar bill called the Protect IP Act that is making its way through the Senate -- effectively promotes censorship.

If SOPA passes, copyright holders would be able to complain to law enforcement officials and get websites shut down. The law would also force intermediaries like search engines and payment processors to withhold their services from targeted websites.

That would be quite a change from the 1998 Digital Millennium Copyright Act, which mandates that companies "act in good faith" to remove content that infringes on copyrights and other intellectual property laws.